Evaluation of EndoAnchor Aortic Wall Penetration After Thoracic Endovascular Aortic Repair

Abstract

Purpose: To analyze aortic wall penetration of Heli-FX EndoAnchors after use in seal zones in the aortic arch or descending thoracic aorta during thoracic endovascular aortic repair (TEVAR). Materials and Methods: From May 2014 to May 2019, 25 patients (mean age 70.5±10 years; 16 women) were treated with TEVAR and adjunctive use of the Heli-FX device in 3 academic vascular surgery departments. Computed tomography scans were retrospectively reviewed to determine the location [arch or descending thoracic aorta (DTA)] of the EndoAnchors and the adequacy of aortic wall penetration, defined as adequate (≥2 mm), partial (<2 mm), or inadequate wall penetration (including loss). Endoleaks, reinterventions, and mortality were assessed. Results: A total of 161 EndoAnchors were deployed (median 7 per patient, range 4–9). Twenty-two EndoAnchors were place in the arch (zones 0–2) and 139 in the DTA (zones 3–5). A larger proportion of arch deployments (27%) had suboptimal penetration compared with the DTA (6.5%; p<0.005), resulting in a 91% adequate wall penetration rate for the series overall. Three EndoAnchors were lost (and only 1 retrieved) in 3 different patients, with no additional morbidity; thus, an overall deployment success rate of 88% was achieved. At a mean follow-up of 16.6±14 months, 4 patients required 5 (successful) reinterventions, including one for a type Ia endoleak treated with chimney TEVAR. One patient died 10 months after treatment due to endograft infection, without an opportunity for surgical correction. Conclusion: EndoAnchors have a higher risk of maldeployment in the arch, though this may be attributable to the small learning curve experience in this location. The best aortic wall penetration for this series was in the DTA, where EndoAnchors proved useful for distal endograft fixation during TEVAR.

Keywords

aortic arch endograft endoleak fixation proximal neck reintervention stent-graft migration thoracic endovascular aortic repair wall penetration

Introduction

Thoracic endovascular aortic repair (TEVAR) is the preferred strategy for treatment of diverse thoracic aortic pathologies,¹ given its minimally invasive nature and recognized comparable risk of complications, such as paraplegia, compared to open surgery. Mid- and long-term results in large series demonstrate durability in anatomically suitable patients; however, reinterventions due to loss of proximal and distal seal compromise procedure success and stability.² Several endovascular techniques have been described to improve the length of seal in the proximal landing zone, such as use of chimneys and periscopes,^3,4 scallops,⁵ fenestrations,^6,7 and branches.^8,9

In terms of arch and thoracic aortic anatomical parameters, angulation¹⁰ and adequate seal zone length (>20 mm) and diameter (<40 mm) have been described as mandatory to achieve adequate seal in the proximal landing zone.¹ However, the fate of the distal landing zone due to anatomical constraints needs to be considered,¹¹ particularly if thoracic aortic aneurysms cause the distal landing zone to encroach upon or cover the celiac axis.¹ In order to overcome the challenges posed by non-ideal landing zone parameters, some authors have described good technical success and safety with adjunctive use of the Heli-FX EndoAnchor System (Medtronic Cardiovascular, Santa Rosa, CA, USA) to improve endograft-to-aorta fixation either primarily or for proximal and/or distal failures.^12,13 Overall, the literature reporting the use of this supplementary approach with TEVAR is scarce.^14,15

This study sought to describe a multicenter experience of patients treated with TEVAR plus supplementary EndoAnchors, assessing deployment positions and how successful EndoAnchors were in achieving complete transmural penetration.

Materials and Methods

Study Design and Patient Sample

From May 2014 to May 2019, 25 patients (mean age 70.5±10 years; 16 women) underwent TEVAR with adjunctive use of the Heli-FX device in 3 vascular surgery departments [designated centers A (n=13), B (n=9), and C (n=3)]. Use of the Heli-FX device was at the operator’s discretion based on anatomical and morphological findings at preoperative computed tomography angiography (CTA). Typically, combinations of the Picture Archiving and Communication System and/or TeraRecon (TeraRecon, Foster City, CA, USA) software were used in center B, while centers A and C employed Osirix software (Pixmeo SARL, Bernex, Switzerland) for case planning. All patients gave written informed consent to the procedures.

Various endografts were used, including the Valiant (Medtronic Cardiovascular; n=10), Zenith Alpha (Cook Medical, Bloomington, USA; n=9), Jotec E-xtra Design (Jotec GmbH, Hechingen, Germany; n=3), C-TAG (Gore Medical, Flagstaff, AZ, USA; n=2), and a Relay Plus (Bolton Medical, Sunrise, FL, USA; n=1). Five patients had a proximal landing zone in the arch (1 in zone 0, 3 in zone 1, and 1 in zone 2). Of the remaining 20 patients, 3 patients had proximal sealing in zone 5 (2 branched stent-grafts and 1 combined fenestrated/branched design for a pararenal abdominal aortic aneurysm).

The anatomical (or other) justification for EndoAnchor usage was short (≤20 mm) landing zones in 13 cases, including 3 with conical morphology (10% diameter change in the intended landing zone) and 1 intraoperative type Ia endoleak. Three patients with atherosclerotic thoracoabdominal aneurysms (1 post dissection) had planned staged treatments in which EndoAnchors improved the fixation of the first (more proximal) thoracic stent-graft. The other 9 patients had severely angulated distal thoracic aortas (n=3), good neck length but long life expectancy (>10 years; n=3), and complex EVAR procedures that were designed based on the use of EndoAnchors (n=3; Table 1).

Table 1.

Cases in Which the Initial Surgical Plan Was Changed due to the Use of EndoAnchors.

Age, y / Sex	Pathology	Initial Strategy	Reason	Final Strategy	Gain	Surgery Data	EAs / Adequate by Imaging	Follow-up, mo
69 / Female	Suprarenal aneurysm (50 mm; fast growth)	Proximal BEVAR seal zone 80–100 mm long	Land endograft beyond DTA curve	Proximal seal 25 mm long + EAs	Less aortic coverage	Jotec E-xtra with 4 IBs	5 / 5	12, no EL
82 / Male	Suprarenal aneurysm (60 mm)	Proximal BEVAR seal zone 80 mm long; CA occluded	Land endograft beyond DTA curve	Proximal seal 25 mm long with 2 renal FENs and ↑ IB for SMA	Less aortic coverage and manipulation of the shaggy DTA	Jotec E-xtra with 2 renal FENs + 1 retrograde SMA IB	5 / 5	6, no EL
60 / Male	Para- anastomotic aneurysm (bifurcated 16x8-mm Gore graft)	BEVAR with 3 EBs (24 F); RRA absent	—	Funnel BEVAR	Avoid access sequelae (trackability); high-risk for open repair	Jotec E-xtra undersized (22 F) plus EAs and aortic cuff (22 F) + EAs	8^a / 8	6, no EL

Abbreviations: BEVAR, branched endovascular aneurysm repair; CA, celiac artery; DTA, descending thoracic aorta; EA, EndoAnchors; EB, external branches; EL, endoleak; F, French; FEN, fenestration; IB, inner branch; RRA, right renal artery; SMA, superior mesenteric artery; ↑, upward.

Four in custom-made stent-grafts plus 4 in aortic cuff.

Device Description and Procedure

The Heli-FX EndoAnchor system delivers small helical “screws” that attach the endograft to the aorta to obtain secure transmural fixation that replicates the pullout force of a surgical anastomosis.^16,17 The thoracic iteration of the Heli-FX system (18-F, 90-cm working length) comes in 3 lengths of deflected tip reach (22, 32, and 42 mm). Each disposable system is for single use only, costing approximately €4760 (£4200).

All procedures required either open surgical or percutaneous femoral access, combined with either hybrid surgical procedures in the aortic arch (debranching, including extra-anatomical rerouting of supra-aortic vessels to achieve a longer landing zone) or totally endovascular procedures in the aortic arch combining covered stents to perfuse the supra-aortic vessels along with the primary aortic endograft. Use of spinal drainage was on a case by case basis.

Definitions and Outcomes

Technical success was adequate penetration of the EndoAnchors, defined as ≥2 mm by Goudeketting et al.¹⁸ Partial penetration (<2 mm) or absence of penetration and device loss were classified as inadequate wall penetration for the purposes of this study. Procedure success was defined as a completed TEVAR with patent arch outflow vessels (when revascularization was required), no type I or III intraoperative endoleak, and no EndoAnchor loss.

The main outcome was the adequacy of aortic wall penetration on the first CT scan in the context of deployment location (arch or descending thoracic aorta). Endoleaks, reinterventions, and mortality were evaluated.

Statistical Analysis

Categorical variables are presented as counts and percentages. Continuous variables are presented as mean ± standard deviation if the data were normally distributed or median (range) if the distribution was skewed. The chi-square or Fisher exact test was used to compare categorical variables. The threshold of statistical significance was p<0.05. Basic numerical outcomes were generated from Microsoft Excel. Statistical analyses were undertaken in Minitab for Windows (version 19; Minitab, Ltd, Coventry, UK).

Results

A total of 161 EndoAnchors were used (median 7 per case, range 4–9), 107 (67%) in the proximal aspect of the endograft and the remaining 54 (33%) to augment the distal landing zone (Figure 1). Overall, there were 15 (9%) EndoAnchors with inadequate wall penetration (91% technical success): 6 (27%) of the 22 EndoAnchors deployed in the arch (zones 0–2) and 9 (6%) of 139 EndoAnchors in the descending thoracic aorta (p<0.005; Table 2). Cases with EndoAnchors deployments in the arch are summarized in Table 3.

Table 2.

EndoAnchor Aortic Wall Penetration in the Arch and Descending Thoracic Aorta.

Penetration	Arch (n=22)	Descending (n=139)	Comments
Complete	16 (73)	130 (94)	Overall success 91%
Incomplete	6 (27)	9 (6)	p<0.005
Partial/none	5	7	p<0.05
Lost	1	2	p>0.99

Data are presented as the number (percentage).

Table 3.

Cases With EndoAnchor Deployments in the Aortic Arch.

Age, y / Sex	ASA	Previous Aortic Repair	Pathology	Neck Diameter, mm / Arch Type	Treatment	EAs / Adequate by Imaging	Follow-up, mo
Zone 0
68 / Male	III	No	Arch aneurysm (60 mm)	15 (conical)	Supra-aortic debranching + TAG endograft	6 (2 outer /3 inner) / 1 lost, 2 PP, 3 adequate	10, no EL
Zone 1
48 / Male¹⁵	II	Patchplasty for aortic coarctation	Patch pseudoaneurysm (76 mm)	14 / III	Cervical debranching + Valiant TEVAR (relining needed due to type IIIa EL)	2 (inner) / 2 adequate	18, no EL
82 / Male	III	No	Arch aneurysm – (78 mm)	16 / III	Cervical debranching + Valiant TEVAR	5 (2 outer/3 inner) / 2 PP, 3 adequate	16, no EL
67 / Female	III	No	Arch aneurysm (60 mm)	20	Carotid-carotid BG + subclavian periscope + Zenith Alpha TEVAR	4 (2 outer/2 inner) / 4 adequate	48, no EL
Zone 2
78 / Male	III	Abdominal graft	Arch aneurysm (62 mm)	17 (conical) / II	Carotid-subclavian BG + Valiant TEVAR	5 (2 outer/3 inner) / 1 PP, 4 adequate	14, no EL

Abbreviations: ASA, American Society of Anesthesiologists; BG, bypass graft; EA, EndoAnchors; EB, external branches; EL, endoleak; TAG, thoracic aortic graft; TEVAR, thoracic endovascular aortic repair.

In total, 3 EndoAnchors were lost in the entire series: 2 migrated and were not retrieved and one was snared, with no morbidity in any case. One EndoAnchor migrated during deployment in zone 4 owing to calcium at the deployment site (Video 1; available in the online version of the article). The EndoAnchor seemed to be caged by the nitinol struts of the endograft and was left in place (Figure 2A). Figure 2B shows a postoperative CT of another EndoAnchor with calcium-related incomplete wall penetration. With no type I/III endoleak, the procedure success of TEVAR with EndoAnchor deployment was 88%. There were no major complications such as paraplegia or stroke.

Over a mean 16.6±14 months of follow-up, 1 patient died 10 months after the index procedure due to endograft infection and severe sepsis without an opportunity for surgical correction. Five reinterventions were required in 4 of the 25 patients, one of them indirectly related to EndoAnchor deployment. The patient with 2 reinterventions was previously treated with TEVAR for type B dissection (4 years before) with aneurysmal evolution of the thoracoabdominal aorta. During treatment of this postdissection (chronic) thoracoabdominal aneurysm (Figure 3A), 3 adjunctive EndoAnchors were placed in a proximal extension (46-mm Valiant Captivia) in a wide, conical zone 3 landing zone. At that repair, open visceral debranching was performed with endograft extension to the abdominal aorta (adjunctive EndoAnchors were used in the distal seal zone but are not included in this study). Postoperative CT (Figure 3B and C) showed inadequate endograft seal due to low deployment, leading to partial outer wall penetration and inadequate inner penetration of the EndoAnchors with a small leak. Subsequent renal thrombosis required thrombectomy; the patient was placed on anticoagulation after repeat thrombosis. Five months later, the patient presented with a symptomatic, massive, type I endoleak and rapid aneurysm expansion; she was urgently treated with a proximally extended new thoracic endograft and subclavian chimney (Figure 3D and E). Sac regression was demonstrated after the chimney TEVAR treatment (Figure 3F1 and F2). Low endograft deployment in a hostile neck was likely the reason for the type Ia endoleak and the entire procedural failure (including EndoAnchors wall penetration).

The remaining 3 reinterventions were due to an iliofemoral bypass infection requiring endograft explantation, a type Ib endoleak treated with distal aortic cuff extension, and a type Ic endoleak from a plug-occluded subclavian artery after carotid-subclavian bypass (the leak was treated with coil embolization).

Discussion

The use of EndoAnchors during TEVAR seems to be useful, safe, and effective, as previously described by Ongstad et al,¹² although appropriate patient selection and some procedure-related considerations are necessary for technical success. Adequate penetration of the EndoAnchors has been reported as the main and only predictive factor for absence of postprocedural type Ia endoleak in selected patients during or after EVAR.¹⁸

Our results demonstrate a high rate of adequate EndoAnchor penetration into the wall of the descending thoracic aorta, but when EndoAnchors were placed in the aortic arch (zones 0–2), the wall penetration success significantly declined. Of note, this was our initial use of EndoAnchors in the arch of only 5 patients, so a learning curve effect is likely. Furthermore, it was difficult to achieve appropriate deflection of the steerable sheath due to more acute angulations in the arch. This may have interfered with obtaining an optimal position for successful EndoAnchor deployment despite biplanar imaging. These technical challenges need to be further explored in larger series.

Three complex EVAR procedures were designed based on the use of EndoAnchors to either shorten the proximal seal zone in 2 cases (Figure 4) or to avoid access-related complications in a case of a branched “funnel” stent-graft. This use of EndoAnchors modified the initial proposed endovascular strategy, avoiding longer endograft designs with a higher risk of paraplegia or high-risk open repair. This might be another use of EndoAnchors to be explored; however, longer follow-up is mandatory to address such a recommendation. In case of failure (eg, type Ia endoleak), prompt identification will (theoretically) require only a proximal aortic tube extension.

Previous studies on the adjunctive use of EndoAnchors during or after TEVAR are scarce, and none has reported aortic wall penetration data yet. The first series reported by Kasprazak et al¹³ involved 6 patients with 28 EndoAnchors (mean 4.7 per patient) with no losses. A later series from the same group²⁰ with 18 TEVAR patients reported 100% technical success but did not report the number of EndoAnchors used specifically in proximal TEVAR nor any postoperative imaging findings. Ho et al¹⁹ treated 6 patients with a total of 50 EndoAnchors (mean 8.3 per patient); 1 patient died after attempts to retrieve a lost EndoAnchor from the distal renal artery resulted in dissection. Although complications during implantation are not frequent, this case illustrates the morbidity that can result from EndoAnchor migration.

The largest series has been described by Ongstad et al,¹² reporting on 54 TEVAR patients with a total of 508 EndoAnchors (mean 9.4) and a technical success of 99.8%, though no aortic wall penetration data was provided. In addition, >100 EndoAnchors described in their series were placed distally in zones 6 to 9.

The use of EndoAnchors in the DTA achieved a greater percentage of adequate aortic wall penetration in our series (93.5%) when compared with the 73% rate for arch deployments, thus representing the safer and more technically effective application.

The case with a chronic postdissection aneurysm requiring reintervention (not attributable to the EndoAnchors and likely related to endograft maldeployment) may suggest a possible contraindication. It seems more than reasonable to avoid the use of EndoAnchors in the acute or subacute phase of an aortic dissection where some inflammation may still compromise the aortic layers. In the chronic phase, this inflammation is supposed to be absent, but the use of EndoAnchors should be judiciously considered. A case has been reported of EndoAnchor application in a patient with Marfan’s syndrome²¹; 5-year follow-up (unpublished) has documented adequate penetration and sac regression.

To our knowledge, there are no studies investigating the number of EndoAnchors needed in a thoracic stent-graft to provide strength approximate to a surgical anastomosis, as bench studies were conducted only for the abdominal aorta.¹⁶ The only surrogate evidence is from experiments suggesting that higher numbers (n=6) deployed circumferentially are better.¹⁷

Limitations

The main limitation of this study is the low number of patients, which prohibits drawing strong conclusions. Moreover, the small experience in the aortic arch reflects the learning curve in this location, which may have affected deployment outcomes. Similarly, it would be interesting to analyze if the adequate penetration of EndoAnchors demonstrated on the first CT is sustained during long-term follow-up, as this will determine the durability of the procedure itself and the role of adjunct EndoAnchor use.

Conclusion

This series indicates that the application of EndoAnchors in the thoracic aorta is safe, with a low loss rate and no major complications that are directly attributable to the devices. EndoAnchors should be judiciously used in the arch, where a considerable number of EndoAnchors do not adequately penetrate the aortic wall, though this may be attributable to the small learning curve experience in this location. When applied in the descending thoracic aorta, EndoAnchors achieve adequate wall penetration in a large percentage of cases, suggesting greater effectiveness for distal endograft fixation during TEVAR.

Footnotes

Declaration of Conflicting Interests

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Andrés Reyes Valdivia is a consultant for Medtronic.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Andrés Reyes Valdivia

Arindam Chaudhuri

Supplemental Material

The online materials are available at

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